The main changes made to most tests are:
*Declarations always include explicit types, not relying on implicit int. The declaration of main in most test programs is changed to be "int main (void) {...}", adding an explicit return type and a prototype. (There are still some non-prototyped functions, though.)
*Functions are always declared before use, either by including a header or by providing a declaration for the specific function. The latter approach is usually used for printf, to avoid requiring ORCA/C to process stdio.h when compiling every test case (which might make test runs noticeably slower).
*Make all return statements in non-void functions (e.g. main) return a value.
*Avoid some instances of undefined behavior and type errors in printf and scanf calls.
Several miscellaneous bugs are also fixed.
There are still a couple test cases that intentionally rely on the C89 behavior, to ensure it still works.
These involve recent standards-conformance patches for printf and scanf, which changed some (non-standard) behaviors that the test cases were expecting.
I also fixed a couple things that clang flagged as undefined behavior, even though they weren't really causing problems under ORCA/C.
